The invention is in the domain of digital multimedia networking. In particular, the invention relates to a method and a digital multimedia network which performs a group management of parameters of audio and video devices.
In contrast to most other industries, digital networks have not gained that much footage in the audio/video industry as expected until today. The reason therefore is neither the lack of available technologies, nor the demand for a digital solution. A problem lies more in the basic understanding of how modern technology can achieve substantial benefit for the user migrating to digital, in a non existing common standard, and how a user can understand and cope with a complex system, moreover made by many different manufacturers. To see digital audio/video networks with the eyes of a user it is generally expected that those systems solve tasks set by the user. During the last years, and due to the lack of a common standard, users who were using or even just experimenting with digital solutions had to either specialize their gear to fit it to custom solutions or reduce the expectations to the digital multimedia system so far that the system was rather more than an audio data transport medium.
Conventional multimedia networks have several disadvantages. There is a lack of integration of connection management with control and monitoring. In many cases an established control and monitoring protocol (for example Crown IQ) is carried by a network such as CobraNet that has its own established approach to media routing (for example an SNMP-based approach). Conventional networks require that a controller discovers all the capabilities of target devices on the control network before it is able to communicate. HiQnet requires that there be a URL from which device information can be obtained. A controller for Crown IQ requires the presence of an Object Information file to determine the capabilities of a device. An ACN controller gets a device's capabilities from an XML-based DDL document that it receives from the target device. An AV/C controller extracts device capabilities from an Audio Subunit descriptor that it gets from the target AV/C device. An AES-24/QSC-24 controller learns of a device's capabilities by requesting its handles and corresponding device paths from the registry. An IEC 62379 device controller uses SNMP to discover device capabilities via the MIB's of devices. A disadvantage with this approach are that small controller devices will typically not have the memory and processor capabilities to enumerate the immense amounts of information needed to describe, as an example, a large mixing console. Further, it is not possible to control several parameters of various devices in a large network without first discovering all the capabilities of all these devices.
HiQnet which is compliant with universal plug-and-play (UPnP) provides facilities for an event notification via the GENA-protocol. A control point can subscribe to events that take place in a device, for example state variable changes. In ACN which is an entertainment controlling monitoring protocol, a subscribe message can be sent by a controller to an apparatus to indicate its interest in a particular property. The apparatus then sends event messages to the controller and the property value changes. In AES-24 transient states of an AES-24 object can cause it to emit one or more AES-24 messages. These transient states are called events. The messages that the AES object emits are defined in an event table and are called event messages.
These conventional protocols according to the State of the Art have several disadvantages. In HiQnet and ACN, a control device indicates what parameters it is interested in. When the value of a parameter changes the controller device is notified of the change. This conventional mechanism allows only for setting up master/slave relationships between parameters.
AES comprises the construction of event tables associated with AES-24 objects. When there is a change in the state of an AES-24 object, it emits messages defined in its event table. This conventional mechanism only allows for the construction of a master/slave relationship where a change in a master parameter causes slave parameters to be changed.
Conventional mechanisms according to the State of the Art do not allow for the construction of parameter groups where a change in the value of any parameter within the respective parameter group results in a corresponding change in the value of every other parameter of said parameter group and where feedback loops do not occur.
Accordingly, it is an object of the present invention to provide a digital multimedia network with a parameter joining mechanism where the device parameters can freely enter and leave the parameter group and where feedback loops do not occur.